heating pad vs warmer

heating pad and warmer both are nouns.

Word	Noun	Adjective	Verb	Adverb
heating pad	Yes	No	No	No
warmer	Yes	No	No	No

As nouns, warmer is a hypernym of heating pad; that is, warmer is a word with a broader meaning than heating pad:

heating pad: heater consisting of electrical heating elements contained in a flexible pad
warmer: device that heats water or supplies warmth to a room

Other hypernyms of heating pad include heater.

heating pad (noun)	warmer (noun)
heater consisting of electrical heating elements contained in a flexible pad	device that heats water or supplies warmth to a room